A representative of a mysterious Chinese oil company was convicted Wednesday on charges that he tried to bribe government leaders in Africa in a case that put foreign officials on the stand to discuss deals, some of which were hatched in the hallways at the United Nations.

The federal trial of Patrick Ho put a spotlight on the methods that a once fast-growing oil company, CEFC China, used to expand its reach from Asia to Africa, Europe and the United States. Mr. Ho, a former government official in Hong Kong who ran a research organization funded by CEFC, was convicted just a little over a year after federal agents arrested him when he was getting off a plane at Kennedy International Airport.

A jury of nine women and three men in Lower Manhattan deliberated for less than a day after a seven-day trial in which Mr. Ho’s lawyers did not call a single witness. Mr. Ho, 69, who has been held in federal custody since his arrest in November 2017, showed little emotion when the verdict was read. As he had throughout the trial, he wore a traditional purple Chinese tunic in court.

Robert Khuzami, the deputy United States attorney for Manhattan, was in the courtroom for the verdict but declined to comment. Lawyers for Mr. Ho also declined to comment.

Mr. Ho was the only one on trial, but the company’s chairman, Ye Jianming, who disappeared in China in March, was also a central figure during the trial. The jury was shown picture of the boyish-looking Mr. Ye, and prosecutors introduced emails in which Mr. Ho said he was in constant communication with the CEFC boss.

Although largely unknown in the United States, Mr. Ye had built CEFC into a company with $37 billion in revenue, and in the process he became one of China’s wealthier men. Now the company is effectively controlled by the Chinese government, and some of its assets are being sold off.

At the start of the trial, a federal prosecutor, Paul Hayden, told the jury that the case against Mr. Ho would be about “greed” and paying bribes to get business deals for CEFC to expand its operations. Mr. Hayden said everything Mr. Ho had done was at the direction of his bosses in China.

Prosecutors said some of the deals had been hatched during meetings at the United Nations where Mr. Ho, who trained as an eye surgeon in the United States, was a frequent visitor during his many trips to New York.

The case appears to have sprung from a broad federal investigation into potential corruption at the United Nations. That investigation led to the conviction last year of Ng Lap Seng, a Macau billionaire, for bribing two diplomats to help him build a conference center in Macau.

The first witness called by prosecutors was Vuk Jeremic, a former foreign minister of Serbia and past president of the United Nations General Assembly, who said he had met Mr. Ho during the final months of his tenure at the United Nations. Eventually, Mr. Jeremic said, he became a paid consultant for CEFC in November 2013, earning roughly $330,000 a year to help “open doors” for the company by lining up introductions to world leaders.

Mr. Jeremic said he had worked closely with Mr. Ho and later with Mr. Ye. But on cross-examination by Mr. Ho’s lawyers, he said that he had done nothing wrong in setting up introductions for the company and that Mr. Ho had never asked him to do anything inappropriate.

The strategy taken by Mr. Ho’s lawyers throughout the trial was to paint the payments to officials in Chad and Uganda as nothing unusual — essentially charitable corporate donations.

“Dr. Ho and his colleagues asked for nothing in return, and the payments were not hidden,” a lawyer for Mr. Ho, Benjamin Rosenberg, told the jury at the start of the trial. “His job was to network and build good will.”

But prosecutors pushed back and portrayed Mr. Ho as a sophisticated wheeler and dealer who was aggressive in trying to get business for CEFC.

The most damaging witness against Mr. Ho was Cheikh Gadio, a former foreign minister of Senegal, who was arrested along with Mr. Ho in the bribery scheme. Prosecutors dropped the charges against him in return for his testimony about his knowledge of Mr. Ho’s alleged attempt to bribe the president of Chad with $2 million that had been hidden in eight gift boxes.

Mr. Gadio testified that he had been shocked by the cash gift that Mr. Ho and the CEFC delegation sought to give Chad’s president, Idriss Déby, during a visit in 2014. Mr. Gadio testified that as the meeting was wrapping up, a women from the CEFC delegation rushed in to remind Mr. Ho and the others to give Mr. Déby the gift boxes they had brought with them.

“I felt it was a bribery attempt,” Mr. Gadio testified.

He said Mr. Déby had also believed the money was a bribe. Mr. Gadio said Mr. Déby had told Mr. Ho and the CEFC delegation that he would not accept the money because he did not want to be seen as a corrupt person.

In the end, Mr. Gadio said, the two sides agreed to allow Mr. Ho and CEFC to recast the $2 million in cash as a donation to the people of Chad and not as a personal gift to Mr. Deby.

The Foreign Corrupt Practices Act permits people to be convicted for merely trying to bribe a foreign leader.

Several jurors declined to discuss the verdict upon leaving the courthouse. The jury deliberated for a little over three hours on Wednesday after getting the case late on Tuesday. The one count on which it acquitted Mr. Ho was a money laundering charge involving the $2 million in cash given to Mr. Deby, but it convicted him on two other counts related to the Chad scheme.

Mr. Ho could spend several years in federal prison, but Judge Loretta A. Preska of Federal District Court could give him credit for the year he has already spent in detention. Sentencing was scheduled for March 14.

A version of this article appears in print on , on Page B7 of the New York edition with the headline: Jury in U.S. Convicts Chinese Oil Company Agent of Bribery. Order Reprints | Today’s Paper | Subscribe